Improve support for int variable evaluation

_fixtures/testvariables.go

@@ -9,16 +9,18 @@ type FooBar struct {
 
 func foobar(baz string) {
 	var (
-		a1 = "foo"
-		a2 = 6
-		a3 = 7.23
-		a4 = [2]int{1, 2}
-		a5 = []int{1, 2, 3, 4, 5}
-		a6 = FooBar{Baz: 8, Bur: "word"}
-		a7 = &FooBar{Baz: 5, Bur: "strum"}
+		a1  = "foo"
+		a2  = 6
+		a3  = 7.23
+		a4  = [2]int{1, 2}
+		a5  = []int{1, 2, 3, 4, 5}
+		a6  = FooBar{Baz: 8, Bur: "word"}
+		a7  = &FooBar{Baz: 5, Bur: "strum"}
+		neg = -1
+		i8  = int8(1)
 	)
 
-	fmt.Println(a1, a2, a3, a4, a5, a6, a7, baz)
+	fmt.Println(a1, a2, a3, a4, a5, a6, a7, baz, neg, i8)
 }
 
 func main() {

proctl/variables_linux_amd64.go

@@ -139,7 +139,7 @@ func (thread *ThreadContext) extractValue(instructions []byte, off int64, typ in
 	case *dwarf.ArrayType:
 		return thread.readIntArray(offaddr, t)
 	case *dwarf.IntType:
-		return thread.readInt(offaddr)
+		return thread.readInt(offaddr, t.ByteSize)
 	case *dwarf.FloatType:
 		return thread.readFloat64(offaddr)
 	}
@@ -225,15 +225,26 @@ func (thread *ThreadContext) readIntArray(addr uintptr, t *dwarf.ArrayType) (str
 	return str, nil
 }
 
-func (thread *ThreadContext) readInt(addr uintptr) (string, error) {
-	val, err := thread.readMemory(addr, 8)
+func (thread *ThreadContext) readInt(addr uintptr, size int64) (string, error) {
+	var n int
+
+	val, err := thread.readMemory(addr, uintptr(size))
 	if err != nil {
 		return "", err
 	}
 
-	n := binary.LittleEndian.Uint64(val)
+	switch size {
+	case 1:
+		n = int(val[0])
+	case 2:
+		n = int(binary.LittleEndian.Uint16(val))
+	case 4:
+		n = int(binary.LittleEndian.Uint32(val))
+	case 8:
+		n = int(binary.LittleEndian.Uint64(val))
+	}
 
-	return strconv.Itoa(int(n)), nil
+	return strconv.Itoa(n), nil
 }
 
 func (thread *ThreadContext) readFloat64(addr uintptr) (string, error) {

proctl/variables_test.go

@@ -29,10 +29,12 @@ func TestVariableEvaluation(t *testing.T) {
 		{"a6", "main.FooBar {Baz: 8, Bur: word}", "main.FooBar"},
 		{"a7", "*main.FooBar {Baz: 5, Bur: strum}", "*main.FooBar"},
 		{"baz", "bazburzum", "struct string"},
+		{"neg", "-1", "int"},
+		{"i8", "1", "int8"},
 	}
 
 	helper.WithTestProcess(executablePath, t, func(p *proctl.DebuggedProcess) {
-		pc, _, _ := p.GoSymTable.LineToPC(fp, 21)
+		pc, _, _ := p.GoSymTable.LineToPC(fp, 23)
 
 		_, err := p.Break(uintptr(pc))
 		assertNoError(err, t, "Break() returned an error")